Formaldehyde modification of cellulose catalyzed by a lewis acid salt and formic acid generated in situ by a peroxide



United States Patent 3,287,083 FORMALDEHYDE MODIFICATION OF CELLU- LOSE CATALYZED BY A LEWIS ACID SALT AND FORMIC ACID GENERATED IN SITU BY A PEROXIDE Henry R. Hushebeck, Wilmington, Del., assignor to Joseph Bancroft & Sons Co., Wilmington, Del., a corporation of Delaware N0 Drawing. Filed Mar. 10, 1964, Ser. No. 350,653 4 Claims. (Cl. &116.4)

This application is a continuation in part of US. application Serial No. 120,923 which was filed on June 30, 1961 and which is now abandoned.

This invention relates to the methylenation of cellulosic fibers such as natural and regenerated cellulose (sometimes hereinafter referred to as rayon) and to blends of cellulosics with other natural and synthetic textile materials. Certain aspects of this invention are particularly concerned with the treatment of materials that contain cellulosic fibers to impart thereto new and enhanced properties and characteristics. Other aspects of this invention are concerned with compositions of matter which are especially adapted for use as catalysts for cellulose methylenation reactions or which facilitate carrying out the cellulose methylenation techniques on cellulosic materials in the form of fibers, filaments, yarns, threads, fabrics, etc., or in the form of finished yarn products.

As will be pointed out in greater detail hereinafter, the catalyst compositions of this invention are specially useful andbeneficial in connection with the formaldehyde finishing of celluolsic textiles. Therefore, the invention will be primarily illustrated in terms of a conventional pad bath finishing process as carried out on a web of fabric; however, by so describing the invention it is not intended that the invention should be construed as being limited to the specific techniques used for illustrative purposes since the catalyst and the process of the invention can be beneficially employed in connection with cellulose methylenation reactions whether they be in connection with the textile industry or some other application involving such reactions.

Even as to textile finishing processes, there are many variations thereof in which the techniques of' the present invention will be found to be useful; all, 'however, have a common procedural similarity in that at some stage, after a reactable aldehydic finishing agent has been applied to the material, it is cured .by heating in the presence of an acid or potentially acid catalyst (i.e., a substance having a cation that will be volatilized on heating to leave a residue that is more acid than the substance itself) which can accelerate the reaction. Therefore, in most instances, I will use the conventional finishing process involving padding, drying, curing and washing to illustrate the techniques of the present invention.

To describe the so-called conventional pad bath treatment in somewhat great-er detail, the fabric web, customarily in the uniformly absorbent pure (greige goods which have been singed, desized, scoured, bleached and washed-and, if desired, thereafter dyed or printed) form, is impregnated in a pad bath and mangled with a solution containing the finishing agents. By controlling the concentration of the finishing agents in the pad bath and adjusting the solution pick-up, a given concentration of finishing impregnants can be applied to or brought into intimate contact with the fabric. Usually, it is desirable to operate under conditions which will provide a solution pick-up of about 65% for cotton and about 80% for rayon; and pick-ups of the order of 50-110% are not uncommon in the textile finishing art. To simplify operations, it is customary for both the finishing agent and its curing catalyst to be deposited from the same bath. Other textile auxiliaries such as softeners, brighteners, tinting agents, and other property modifiers which it may be desirable to incorporate in the fabric at this stage can also be included in the pad bath. The impregnated fabric is cured by heating in the presence of a curing catalyst. To effect the cure in conventional heating equipment, temperatures are usually employed which will enable the curing to be completed in about 30 minutes or less. However, in some instances, it is possible to effect the cure over longer periods provided special heating equipment and techniques are employed; in most cases conventional curing equipment will permit the employment of time-temperature relationships between and comparable to those effected by 30 minute cures at F. and 30 second cures at 400 F.

The use of aldehydes as textile finishing agents is not per se a new technique; the reactions of al-dehydes with cellulose involve a long history of unsuccessful efforts to effectively control the reaction to a point where commercial processing of cellulosics with various aldehydesparticularly formaldehydewas feasible. Theoretically, it is possible to react cellulose wit-h a quantity of formaldehyde equal to about 17.2% of the weight of the cellulose. Introducing this quantity of formaldehyde into a cellulose fabric is a totally impractical procedure the fabric will be completely destroyed. Many of the older fabric finishing processes utilizing formaldehyde as a stabilizing influence required the reaction of formaldehyde in quantities in excess of 2% in order to obtain the desired results. However, getting such quantities of formaldehyde permanently into the fabric required unduly harsh curing conditions which degraded the cellulose to a point where the resultant fabric was exceptionally tender. In this regard, rayon is inherently more resistant to acid than cotton, therefore, it was less subject to tendering and prior to about 1958, commercial methylenating techniques were for this reason exclusively confined to the treatment of rayonhowever, even with rayon the tendering imposed serious limitations on efficient and effective operation. Probably the most objectionable feature of the cellulose methylenation processes heretofore proposed was the fact that the reaction was very unpredictable and exceedingly difiicult to control and impart reproducible results. In finishing process proposals utilizing methylenating agents such as formaldehyde and other aldehydes, the conventional catalysts were rather unsatisfactory even though extreme efforts were made to regulate the curing conditions. .It was practically impossible to obtain uniform properties throughout the fabric; some portions would be objectionably tendered and in other portions, the degradation would be less perceptible; the resilience, durability and other properties were also found to vary quite unpredictably. In the period from the early 1930s to about 1958, the much more readily controllable thermosetting resins were almost exclusively used as fabric stabilizing agents and little interest was shown in methylenation reactions despite the known desirability of using formaldehyde and other methylenating agents as stabilizing agents. In recent years, the textile industries interest in formaldehyde as a finishing agent has been reactivated. Techniques have been developed which have led to greater predictability of results. For the most part, these recent developments have involved attempts to develop wet phase methylenation techniques employing very strong acids and curing at room temperature. Another line of attack has involved the development of catalysts having special characteristics which make them more suitable for cellulose methylenation. Both lines of attack have been successful to a degree in minimizing the tendering of the cellulose,

but the wet phase treatments cannot be used when the treatment is one that is also intended to impart enhanced dry crease resistance.

Thepresent invention is concerned primarily with a new type of catalyst for carrying out the treatment whereby the property variationsdiffer. from those obtained where conventional acid or acid forming substances are employed as the catalyst.

By the use of the new catalyst system and techniques of this invention an unusually high level, of .wash and wear properties (including a high degree of both wet catalyst system and process of this invention for the methylenation of natural cellulose does not significantly increase the cation activity of the material. Many prior art methylenation catalysts materially increase the cationic activity of methylenated cellulosic fabrics and render them more susceptible todiscoloration during alkaline washings due to their increased tendency to pick up iron, cationic dyes or other colored cations from the wash liquor. Of great significance, is the controllability of the process; where the novel catalyst of this invention is employed uniform finish effects can be obtained and reproduced in the mill to a degree which heretofore could not be duplicated with conventional acid and potentially acid catalysts of the type heretofore used in methylenation treatments.

Where the fabric undergoing treatment is rayon blended with other textile fiber materialsparticularly with man-made synthetic fibers such as acetate, acrylic, modacrylic, nylon, nitrile, olefin, polyester and the 'like,'still additional benefits are obtained where the catalyst system of this movement is employed in lieu of convenout resorting to a heat setting operation; and a finish is obtained which has a very pleasing readily variable hand.

In accordance with the invention, the catalyst system is one which contains an oxidizing agent component and a salt component having special characteristics hereinafter described and is primarily intended for use in met-hylenation reactions where formaldehyde is the methylenating agent. The system can, however, also be used where other aldehydes such as glyoxal, a-hydroxyadipaldehyde, glutaraldehyde, and the like are employed as the methylenating agent. It can also be effectively used with materials or compounds which, upon heating, especially in the presence of acids, liberate free aldehydes, the methylol acetones and other methylol ketones, paraformaldehyde, trioxane and the like, are typical of aldehyde liberants whichare useful materials in the finishing and treatment of textiles.

The salt components of the catalyst constitutes the primary source of the acid employed or developed for the curing environment. In accordance with the invention it is preferred to employ the chlorides and nitrates of polyvalent metals.

Within this group magnesium nitrate appears to give the best results, but it is closely followed by the cadmium, calcium, barium and zinc nitrates in approximately 4 the order mentioned. Other nitrates which are operable are those of strontium, cobalt, zirconium, nickel, and chromium. Chlorides can also be used, but they do not in all instances appear to work as well as the nitrates.

Chlorides which have been found to be operable include cobaltous chloride, nickel chloride, aluminum chloride,

magnesium chloride, calcium chloride, zinc chloride, stannic chloride, titanium trichloride, zirconium oxychloride and chromic chloride.

Where white goods are to be finished, it is preferred to employ those metal salts which form substantially colorless aqueous solutions.

The aforementioned group of salts are preferred because they are normal salts of polyvalent metals with Lewis acids (i.e., electron acceptors) that have special characteristics that make them especially useful in methylenation reactions-to wit: (1) aqueous solution of the catalyst will not significantly accelerate either dry or wet phase methylenation of cellulosic materials at temperatures below 200 F.; (2) when the salts are employed in concentrations of about 1% by weight of the meth-.

' 270 F. for 3 minutes; (a). the anion will undergo hymetals.

drolysis and/or dissociation to liberate acid in quantities that will accelerate the reaction of the cellulosic material with the aldehyde and (b) at the same time, leave a residue in the cellulosic material that is less acid than the salt.

It appears that such characteristics can be possessed by salts other than the chlorides and nitrates of polyvalent that have a hydrolyz'able or dissociable acidic anion and that aldehyde finishing impregnants are highly volatile and it is desirable to effect the cure at low temperatures (e.g., about 200300 F.) rather than at :higher temperatures; and under no circumstances should curing temperatures be employed which could scorch the fabric undergoing treatment. Attempts to compensate for the slow rate of acid liberation by increasing the concentration of the acid salt have not been found satisfactory because it also increases the danger of fabricdamageparticularly strength lossesdue to hydrolysis oracid degradation of the fabric. Hydrolysis or acid degradation involves changing the chemical nature of the textile material and the extent of hydrolysis is governed by several factors including the type of" catalyst, its concentration, and the curing conditions (time and temperature). employed.

As the oxidizing agent in the catalyst system of the invention, I prefer to employ 'hydrogen peroxide itself. However, other materials that will serve as a source of hydrogen peroxide either by reacting to form hydrogen peroxide or decomposing to liberate hydrogen peroxide when in a neutral or acidic aqueous solution (either with or without heating) can also be used, for example, the alkali metal persulfates and similar acting peroxy acids and salts of the peroxy acids.

A preferred catalyst composition prepared in accord ance with this invention is an aqueous solution containing magnesium nitrate as the salt component and either hydrogen peroxide or potassium persulfate as the oxidant.

For the methylenation of cottons, optimum results are obtained by the use of the catalyst components ina molar ratio of about 1 mole of the magnesium nitrate to 2 moles of the hydrogen peroxide (e.g., a weight ratio of about 13:10 expressed in terms of magnesium nitrate However, many of the metal salts of Lewis acids hexahydrate and 35% hydrogen peroxide) and in concentrations which provide a 100 gallon pad bath with from about 4-6 pounds of the 35% hydrogen peroxide.

For the methylenation of rayon, and rayon blends, optimum results are obtained by the use of the catalyst components in a molar ratio of about 3 moles of magnesium nitrate to 4 moles of hydrogen peroxide (e.g., a weight ratio of about 2:1 expressed in terms of magnesium nitrate hexahydrate and 35% hydrogen peroxide) and in concentrations which will provide a 100 gallon pad bath with from about 4-8 pounds of 35% hydrogen peroxide.

In either case, changing the molar ratio of the components does not render the catalyst ineffective, but causes the catalytic function to approach that of the particular individual component whose concentration has been increased.

It is possible to replace the hydrogen peroxide with a molecular equivalent of potassium persulfate. However, when using potassium persulfate as the source of the hydrogen peroxide, best results are obtained with somewhat different concentrations and molar ratios.

It is also possible to replace the magnesium nitrate with a stoichiometric equivalent of one or more other salts such as magnesium chloride, calcium nitrate, zinc nitrate, zinc chloride and the like. When such substitutions are effected, the concentration of the catalyst in the bath will have to vary depending on the relative acidity of the substituted salt as compared to that of magnesium nitrate. Thus, if the substituted salt is relatively more acid than magnesium nitrate, the total weight used in the bath will have to be reduced accordingly and vice versa. The following Tables I-IV set forth operable, preferred and optimum ranges and concentrations for the formaldehyde, the oxidant, and the salt component of pad baths and for the weight ratios of the catalyst components in the pad bath where the baths are to be used in the methylenation of cotton or in the methylenation of fabric consisting entirely of or blended with rayon.

TABLE I.-RAYON AND RAYON BLENDS Operable Preferred Optimum 37% Formaldehyde Over 80# 100150# 115125#. 35% B 0 318# 442? 48#. Mg(NO3)z6HgO 420# 6-18# 816#. Weight ratio oxidant 1/O.2 to 1/6. l/0.8 to l/3..- 1/2. Water to make 100 gal 100 gal 100 gal.

TABLE l'L-COTTON Operable Preferred Optimum 37% Formaldehyde Over 150#, 150300# 275300#. 35 H 0 2-1 2.5-7# 4-6. 1Vlg(N03)26HzO 2-10 3.2-9 5.27.8#. Weight ratio oxidant/salt 1/1 to 1/3 1/1 to 1/3 10/13. Water to make 100 gal 0 gal 100 gal.

TABLE III.RAYON AND RAYON BLENDS Operable Preferred Optimum 37% Formaldehyde Over 80# 100-150# 115125#. K232 g 3-12 612# 81Q#. Mg(NO3) zfiHzO 2-18 6-12# 810#. Weight ratio oxidant/salt l/0.2 to 1/2 1/2 to 2/1 1/1. Water to make 100 gal 100 gal 100 gal.

TABLE IV.COTTON Operable Preferred Optimum 37% Formaldehyde Over 150# 150-300# 175-2251;. Kgsgog 18# 28# 26#. Mg(NO )gfiH O 0.58# 1- 13#. Weight ratio oxidant/salt 12/1 to 1/2..- 6/1 to l/ 1. Water to make 100 gal 100 gal 100 gal.

Catalyst systems containing the salt-oxidizing agent combination prepared according to the present invention have also been found to be effective in the curing of fabrics where, in addition to the methylenating agent, the impregnating bath also contains a cyclic methylol urea (e. g., methylol ethylene ureas, methylol acetylene diureas, methylol dihydroxyethylene ureas and methylol triazones). The system of this invention is also effective as a curing catalyst when the methylenation and resination with the aforementioned cyclic methylol ureas are carried out as sequential rather than simultaneous treat ments. Such treatments with methylenating agents when coupled with resinati-on give high resilience and wash and wear properties.

In cases where it is desirable to do so, other auxiliaries can be incorporated in the pad bath containing the instant catalyst system, for example, it is possible to incorporate an acid polymerizable acrylic emulsion such as Rhoplex HA-8 in the catalyst master batch in proportions which will provide the desired concentration of the acrylic emulsion in the pad bath-usually in concentration of about 4 to 8% of total pad bath weight. Rhoplex HA-8, Resyn 25-2833, Rhoplex HA-4 Rhoplex HA-l2 and Rhoplex B-27 are suitable for this purpose. They are acid polymerizable acrylic copolymer emulsions with a non-ionic emulsifying agent. These emulsions are used to modify the hand and in certain situations enhance resilience and wash and wear properties. The acrylic emulsions are particularly useful supplemental auxiliaries for improving the Wash and wear propertiesparticnlarly the wet wash and wear; they also serve to enhance the resilience and bulk up the hand of the fabric.

It is usually also desirable to employ a wetting agent such as Triton Xl00 (an alkaryl polyether alcohol) in the pad bath to provide for a more uniform distribution of the impregnants throughout the fabric. Customarily, the wetting agent comprises from 0.1 to 0.5% by weight of the bath.

In making up pad baths for methylenating treatments with formaldehyde, the catalyst is preferably added to the mix containing the formaldehyde just before using and the bath is then brought to the desired volume and thoroughly mixed. However, the baths containing the catalyst are highly stable despite the presence of the acidic catalyst and can, in closed systems, stand for prolonged periods without deleterious effects.

The following examples will serve to illustrate in greater detail some of the various features of the invention. While the following examples are primarily con- 'cerned with treating cellulosic fibers to impart an allover non-mechanical finish effect to the fabric, the process and catalyst system should not be deemed to be limited-thereby. Both the method and the catalyst system can be effectively utilized in any other type of fabric finishing process where it is necessary to cure one or more acid curable finishing agents which have been applied to the fabric. Such other processes may involve localized or all-over application of the finishing agent; and if desired, the process may also involve mechanically treating the fabric to alter the shape and relative disposition of the yarns-as for example by calendering, pleating, ruffling, compressive shrinkage and the like.

In the accompanying Table V, the pad bath formulations employed in Examples 1-17 are expressed in grams/800 ml. of bath. In these examples, the fabric undergoing treatment was a scoured and bleached viscose rayon challis. The fabric samples were padded through the bath under conditions giving a solution pick-up of about and the fabrics were then carefully dried. After curing for five minutes at 275 F., the fabrics were washed with /2% caustic soda and wetting agent (Triton X-lOO).

TABLE V ExampleNo. 1 2 a 4 5 Formaldehyde (37%) K O The catalyst systems of potassium persulfate-magnesium nitrate (Example 5) and hydrogen peroxidemagnesium nitrate (Example 7) generally give the best all around properties for the treatment of rayon. The persulfate system of Example 5 gives a little better dry resilience and tends to fix more formaldehyde on the fabric than does the hydrogen peroxide-magnesium nitrate system (Example 7).

However, there is a ten-,

dency for the persulfate system to give a poorer white I and to have more sensitivity to alkaline wash discoloration. The peroxide system except for the two points mentioned above gives. equivalent performance and has a better white and is considerably less sensitive to alkaline wash discoloration.

When the persulfate is used alone (Examples 1, 3 and 9) even in double quantities, the performance and properties are somewhat improved over the untreated but are inferior to results obtained with the acid salt-oxidant combinations. Hydrogen peroxide alone in even more than double quantities (Examples 6 and 8) gives less improvement over the untreated than persulfate. Mag nesiurn nitrate alone (Examples 2 and 4) gives an intermediate performance similar to the use of larger quantities of potassium persulfate. None of the materials alone give commercially satisfactory performance. Deletion of the acrylic'emulsion (Examples 16 and 17) fromeither basic formulation (Examples 5 and 7) shows a reduction in the wash-wear and resilience.

The substitution of other metallic salts'for magnesium nitrate in varying quantities (Examples 11-14) gave approximately the same physical properties with slight variations in performance. However, for wash wear performance equivalent to magnesium nitrate, the strengths are generally inferior.

Ammonium chloride-persulfate (Example 10) gives results which seem to be typical of ammonium salts, in that a high level of performance is obtained with very small amounts, but the cloth is weakened and also objectionably discolored.

The use of a mixture of hydrogen peroxide and potassium persulfate (Example 15) gives satisfactory performance intermediate to that obtained by the use of either oxidant alone (Examples 5 and 7).

The curing of rayons with these catalyst systems of this invention involves a slight variation from the usual rule of thumb time-temperature relationship. Our experience has shown that time is more important than temperature. In other words, we can get a better cure at 275 F. for 5 minutes than is obtained when the fabric is heated for 3 minutes at 300 F. Rayon is, generally speaking, more amorphous than cotton and therefore, aTonger interval of heating is necessary in order to fix the formaldehyde uniformly throughout the fibef. In mill practice on rayon, cures over 300 F. with the catalyst systems of this invention have not proved to be necessary for desirable results and usually destroy the favorable balance of properties obtained. Lower temperatures generally require slightly longer times (250 F. at 6-7 minutes).

Example 18 A 136 x 64 cotton broadcloth fabric running 2.72 yards per pound with a greige width of 48% inches was singed, des led, scoured, bleached and mercerized before being padded in a bath containing:

Lbs.

Formaldehyde (37%) 300 Hydrogen peroxide (35%) 5.0 Magnesium nitrate .6H O 6.5 Rhoplex HA-8 25.0 Triton X-100 2.0

Water to make 100 gallons.

Example 19 An x 80 square unmercerized cotton fabric running four yards to the pound was padded in a bath containmg:

- Parts Formaldehyde 200 Potassium persulfate 4 Magnesium nitrate 2 Triton X- 1 Water to make a total of 800 parts.

The pH of the mix was 3.5. The solution pick-up was adjusted to about 80%. The fabric was then carefully dried. Portions of the dried fabric were cured for three minutes at 300 F., and other portions were cured for three minutes at 280 F. The pH of the fabric cured at 280 F. was 4.2 and of the fabric cured at 300 was 4.0. The fabrics were washed with A sodium perborate and wetting agent and thereafter dried.

The properties of the treated fabric were similar to those obtained in Example 18. Further, the portions cured at the higher temperature exhibit a greater degree of improvement than in the case of the fabric cured at the lower temperature.

Example 20 A fabric having a cotton warp and a viscose regen-- erated cellulose filling was padded through a bath con- Water to make a total of 800 parts.

Example 21 A fabric consisting of 65% Dacron (polyester) fibers and 35% viscouse rayon fibers was heat set and thereafter padded through a bath containing:

Parts Formaldehyde 120 Potassium persulfate 9 Magnesium nitrate 9 Triton X-100 2 Water to make a total of 800 parts.

The solution pick-up was adjusted to about 80%. The fabric was carefully dried and then cured for five minutes at 275 F., and thereafter washed. The dry resilience and the wash and Wear properties of the resulting fabric were enhanced. In addition, a high degree in the stabilization of both the Warp and filling were achieved.

I claim:

1. In a process of methylenating rayon and rayon blends involving reacting the rayon with formaldehyde at elevated temperatures in the presence of an acid catalyst the improvement which comprises employing a composition comprising 80 to 150 pounds 37% formaldehyde, 3 to 18 pounds 35% hydrogen peroxide, 4 to 20 pounds magnesium nitrate hexahydrate and water to make 100 gallons, the weight ratio of the hydrogen peroxide to the magnesium nitrate being 1/ 0.2 to 1/6, as a pad bath to apply the formaldehyde and catalyst to the rayon.

2. In a process of methylenating rayon and rayon blends involving reacting the rayon with formaldehyde at elevated temperatures in the presence of an acid catalyst the improvement which comprises employing a composition comprising 80 to 150 pounds 37% formaldehyde, 3 to 12 pounds potassium persulfate, 2 to 18 pounds magnesium nitrate hexahydrate and water to make 100 gallons, the weight ratio of potassium persulfate to the magnesium nitrate being 1/ 0.2 to 1/2, as a pad bath to apply the formaldehyde and catalyst to the rayon.

3. In a process of methylenatin-g cotton involving reacting the cotton with formaldehyde at elevated temperatures in the presence of an acid catalyst, the improvement which comprises employing a composition comprising 10 150 to 300 pounds of 37% formaldehyde, 2 to 10 pounds 35% hydrogen peroxide, 2 to 10 pounds magnesium nitrate hexahyd-rate and Water to make gallons, the Weight ratio of the hydrogen peroxide to the magnesium nitrate being 1/1 to 1/ 3, as a pad bath to apply the formaldehyde and catalyst to the cotton.

4. In a process of methylenating cotton involving reacting the cotton with formaldehyde at elevated temperatures in the presence of an acid catalyst, the improvement which comprises employing a composition comprising to 300 pounds 37% formaldehyde, 1-8 pounds potassium persulfate, 0.5 to 8 pounds magnesium nitrate hexahydrate and water to make 100 gallons, the weight ratio of the potassium persulfate to the magnesium nitrate being 12/ 1 to 1/2, as a pad bath to apply the formaldehyde and catalyst to the cotton.

References Cited by the Examiner UNITED STATES PATENTS 995,852 6/ 1911 Eschalier 8116.4 2,108,520 2/ 1938 Wolf et al. 8116.4 2,160,391 5/1939 Reichert et al. 23207.5 2,512,195 6/ 1950 Bener 8--116.3 2,530,175 11/1950 Pfefier et a1 8-ll6.-4 2,957,746 10/1960 Buck et al. 8116.3 3,089,747 5/1963 Welch 8116.4 3,094,372 6/ 1963 Hibbert et al 8-116.4 3,113,826 12/1963 Dual et al. 8116.4 3,118,725 1/1964 Henry et al 8116.4 3,139,322 6/1964 Hushbeck 8116.3 3,165,374 1/1965 Hushbeck 8-116.4

FOREIGN PATENTS 13,751 1913 Great Britain.

460,208 1/ 1937 Great Britain.

488,095 6/ 1938 Great Britain.

498,763 1/1939 Great Britain.

5 47,846 9/ 1942 Great Britain.

565,337 11/ 1944 Great Britain.

649,019 1/1951 Great Britain.

727,890 4/ 1955 Great Britain.

NORMAN G. TORCHIN, Primary Examiner.

ALEXANDER D. RICCI, Examiner.

J. C. CANNON, Assistant Examiner. 

1. IN A PROCESS OF METHYLENATING RAYON AND RAYON BLENDS INVOLVING REACTING THE RAYON WITH FORMADEHYDE AT ELEVATED TEMPERATURES IN THE PRESENCE OF AN ACID CATALYST THE IMPROVEMENT WHICH COMPRISES EMPLOYING A COMPOSITION COMPRISING 80 TO 150 POUNDS 37% FORALDEHYDE, 3 TO 18 POUNDS 35% HYDROGEN PEROXIDE, 4 TO 20 POUNDS MAGNESIUM NITRATE HEXAHYDRATE AND WATER TO MAKE 100 GALLONS, THE WEIGHT RATIO OF THE HYDROGEN PEROXIDE TO THE MAGNESIUM NITRATE BEING 1/0.2 TO 1/6, AS A PAD BATH TO APPLY THE FORMALDEHYDE AND CATALYST TO THE RAYON. 